Stabilized gasoline



Jan. 19,v 1943.v R. H. `R'osENwALD Erm. 2,308,781

STBILIZED GASOIINE original Filed April 3o, 1958 5 v 10 v 70ML ffl/02 a/VAmMs//V sI/sT/TUr/A/ @pay/as' Patented Jan. 19,4 1943 STABILIZED GASOLINE Robert il. Rosenwald and Joseph A. Chenicek,

Chicago, Ill., assignors to Universal Oil. Prody u'cts Company, Chicago, Ill., a corporation of Delaware Original application April 30, 1938, Serial No. 205,356, now Patent No. 2,250,501, dated July 29, 1941. Divided and this application April 8, 1941, Serial No. 387,465

4 Claims.

This application is a division of our co-pending application Serial No. 205,356 filed April 30, 1938, now Patent No. 2,250,501 of July 29, 1941.

This invention relates more particularly to a process of treatment applicable to lower boiling fractions of cracked distillates within the gasoline range although it is also applicable to heavier distillates produced by the fractionation of cracked products and to corresponding fractions from the primary distillation of crude petroleums or other hydrocarbonaceous materials such as coal and shale.

The process is concerned specifically with the use of certain denite types of inhibitors to materially arrest the deterioration to which hydrocarbon distllates containing appreciable quantities of olenic and other unsaturated hydrocarbons are subject. AThe art of using inhibitors in unstable gasolines is now one of comparatively long standing and a large number of individual compounds and classes of compounds have been developed for practical use, all of which apparently possess the characteristic of being more or less readily oxidizable so that the peroxidic comto include the use of such compounds as phenols,

amines, `and aminophenols and crudeyprimary products containing these compounds, and no basic vclaim is made herein to the broad use of any of these classes. 'Ihe present invention is Cil ortho, meta, or para position with respect to me hydroxyl group although in general the compounds of greater potency follow within the general class of those of the para substituted variety.

We have shown as a, result of considerable number of experiments in which differently substituted alkyl aminophenols were tested that greater advantages are gained by utilizing as inhibitors alkyl aminophenols in which there is substitution of both amino hydrogens by diierent alkyl groups over utilizing those characterized by substitution with identical groups or by substitution of one amino hydrogen with one group even though the total number ofl carbon atoms in the substituting groups is the same in all cases. The advantages gained include greater inhibiting potency, greater solubility in gasolinas and improved resistance to extraction with water or alkaline solutions to which gasolines may be exposed during storage-conditions, on account of e the decreased solubility of the mixed substituted compounds. These advantages were unexpected and unpredictable from any study of chemical' effects will be indicated in a succeeding illustraspecially concerned with a limited group of compounds which have been found to possess exceptionally 'good inhibiting potency combined with resistance to accidental removal by contact with water orcaustic soda which occurs at many points in the storage systems ci oil refineries.

In one speciilc embodiment the present invention comprises the treatment or unstable gasolines, particularly cracked gasolines, to materially arrest the deterioration thereof by adding to tive and numerical section.

Compounds of the present character are made from amino-phenols by successively replacing the amino hydrogens with the desired alkyl groups.

methyl chloride N-methyl-isoamyl-pamino phenol In this method the reaction may be brought about for 12 hours under atmospheric pressure.

Parts by weight Methyl-p-aminophenol sulfate 45 rSodium bicarbonate 52 ll-Octyl bromide 45 Ethyl alcohol 200 After the period of digestion the total reactants were poured into water and the aqueous and oil layers were extracted with a small volume of ether. Ether extracts were then heated to volatilize the ether and then distilled under an absolute pressure of 4 mm. of mercury. AThe primary distillation gave the results shown below Fraction 1 2.5 parts by weight. Boiling range 12o-167 C.

VFraction 111 32.9 parts by weight. Boilingrange 168-170 C. Residue 5.0 parts by weight 1 N-n-octyl-N-methyl-p-aminophenol.

Redistillation of fraction II which corresponded to a 70% yield of the desired compound showed a constant boiling point of 163 C.

The amounts of the present classes of compounds' which are necessary to properly inhibit the deterioration of unstable gasolines will obviously depend uponthe instability of the particular gasoline at hand and the potency of the individual'compound selected. As a rule it is seldom necessary to employ more than 0.1% of any of the inhibiting compounds and usually percentages of the order `of 0.01% are sulcient. Since the present compounds areV considerably more soluble in gasoline than those in which :the

alkyl groups are they same, the addition of the necessary small amounts to'gasoline contained in large storage tanks is more simple and more easily effected than when inhibitors of lesser solubility are employed in which cases it is frequently necessary to employ a long period of mechanical group. Thus. it will be observed that the combe used in gasolines which are not dry or which are stored over water or alkali to prevent corro- A sion of the tank bottoms. These inhibitors may be'also employed in conjunction with other compounds of specific character such as the dyes which are frequently used to mask the slightly yellow tinge characteristic of cracked gasoline with various types of antiknock compounds such as tetra ethyl lead and with special types of inhibitors which are directed-to the preservation of color or other specific properties. l

The attached curves, designated as Figure l, are introduced to exemplify the more general aspects of the invention. These curves were made up to indicate the data obtained in a large number of experiments. Referring to the gure it will be seen that curve 1 shows the variation oi.' the eiective inhibitor ratio with the total carbons in substituting groups of mono-alkyl substituted aminophenols. Curve 2 shows the same relationship when di-alkyl substituted oompounds are considered in which the substituting groups are the same. Curve 3 it will be observed is higher than the other two at all points below 18 oarbon atoms and shows graphically the data obtained with mixed alkyl substituted Vaminophenols. In each of the cases shown in curve 3 one of the substituent groups was a methyl pound of the present invention, namely, N-methyl-N-hexyl-p-aminophenol, which has a total of '7 alkyl carbon atoms in vsubstituting groups, has an effective inhibitor ratio of approximately 1.35. From these data it is obvious that the most effective inhibitors are those di-substituted aminophenols in which the substituting groups are different.

We claim as our invention:

1. A process for the treatment of gasolines subject to deterioration of their desirable properties on storage, which comprises adding there- A to amounts of N-methyl-N-hexyl-aminophenols` equal to less than 0.1% by weight of said gasoline.

2. A process for the treatment of gasolines subject to deterioration of their desirable properties on storage, which comprises adding thereto amounts of N-methyl-N-hexyl-p-aminophenols equal to less than 0.1% by weight of said gasoline.

3. A process for the treatment of cracked gasolines subject to deterioration of their desirable mixing or an auxiliary solvent to assist in the dispersion ofthe inhibiting' compounds. In the present instance a minimum of mixing is required and solvents are not necessary. In addition, owing to the relatively low walter and alkali solubility of the preferred compounds, they may properties on storage,` which comprises addingthereto amounts of methyl-N-hexyl-p-aminophenols equal to less han l0.1% by weight of said gasoline.

4. Motor fuel comprising unstable gasoline containing a relatively small amount of N-methyl-N-hexyl-p-aminophenol.

norxrt'r.` H: RosENWALD.

JOSEPH A. 'CHENICEK 

